article: Mr. Evans lives in a city. He was a math teacher three years ago. He taught well and his students liked him. So he decided to work in the middle school all his life. But a terrible accident changed his fortune .
  One spring he took his class to visit a place of interest. The children saw a lot of interesting things and had a good time there. But on their way to school, their bus was hit by a truck because the young driver was drunk . Five students died and more than half of the children were injured in the accident. He didn't know how it had happened and was very sad about it and after he came out of hospital, he left the school and became a policeman. He tried his best to stop the drivers from breaking the traffic regulations . He worked hard and was strict with the drivers. So they were afraid of him.
  One afternoon it was very hot. Mr. Evans was on duty. He was standing at the crossing and watching the traffic. Suddenly he saw a car rushing towards the crossing. It ran so fast that it almost hit a man on a bike. He stopped it at once and saw a girl in it.
  "Show your license to me, madam," said Mr. Evans.
  The girl handed her bag to him and said: "Please look for it in it. I can't see anything without glasses."
question: What was Mr. Evans' job three years ago?
options: policeman a math teacher a guide a drive